If you solely rely on Twitter to post job openings, you might be unknowingly discriminating against older workers.

Since Twitter users are predominantly on the younger side, employment experts say companies that post all their job openings on the social networking site could be shunning job seekers over the age of 40.

"Potentially, you could be excluding a protected class by only using one social media outlet," says Eric B. Meyer, a partner at Dilworth and Paxton law firm. He says even though the practice might not be superficially discriminatory, it could be discriminatory in its application.

According to Karen Elliot, an employment law attorney at Sands Anderson, if you have more than 20 employees and use Twitter as the primary means of job postings, you could be hit with a claim under the Age Discrimination in Employment Act of 1967.

"The [U.S. Equal Employment Opportunity Commission] enforces the ADEA and considers the ADEA to prohibit an employer from using neutral employment policies and practices that have a disproportionately negative impact on applicants or employees age 40 or older, if the policies or practices at issue are not based on a reasonable factor other than age," writes Elliot at VirginiaWorkplaceLaw.com.

Elliott says such a case would be difficult to prove because a person would have to show that they were discriminated against because of their age. Still, you probably don't want to spend a lot of time or money defending yourself, so it's better to cover your bases in the first place.

Both Meyer and Elliot say the best way to protect yourself is to choose to advertise on multiple social networks. They recommend using Facebook and LinkedIn, which attract older job seekers.